Brain Tumor Res Treat 2017;5(2):110-115 / pISSN 2288-2405 / eISSN 2288-2413 CASE REPORT https://doi.org/10.14791/btrt.2017.5.2.110
Pituicytoma with Significant Tumor Vascularity Mimicking Pituitary Macroadenoma
Hyuk Ki Shim1, Seung Heon Cha1, Won Ho Cho1, Sung-Hye Park2 1Department of Neurosurgery, Pusan National University School of Medicine, Pusan National University Hospital, Busan, Korea 2Department of Pathology, Seoul National University College of Medicine, Seoul National University Hospital, Seoul, Korea
A 19-year-old man presented with bitemporal hemianopsia and was found to have a large sellar and Received July 23, 2017 suprasellar tumor, resembling a pituitary macroadenoma. Emergency transsphenoidal approach was Revised August 19, 2017 attempted because of rapid visual deterioration with headache. However, the approach was compli- Accepted August 21, 2017 cated and stopped by uncontrolled hemorrhage from the tumor. After conventional cerebral angiogra- Correspondence phy and recognition of an unusual pathology, transcranial approach was achieved to prevent permanent Seung Heon Cha visual loss. The final pathological diagnosis was pituicytoma with epithelioid features. Pituicytoma is a Department of Neurosurgery, rare low-grade tumor (WHO Grade I) of pituicytes involving the sellar and suprasellar region, and origi- Pusan National University nating from special glial cells of the neurohypophysis. Because of the high vascularity, the firm consis- School of Medicine, tency, and invasion to surrounding neurovascular structures, a pituicytoma should be included in the Pusan National University Hospital, differential diagnosis of a mass in the sellar and suprasellar area if the tumor shows high enhancement 179 Gudeok-ro, Seo-gu, Busan 49241, Korea with vascular components. We report a case of rare pituicytoma mimicking a pituitary macroadenoma Tel: +82-51-240-7257 with massive hemorrhage to disturb surgery. Fax: +82-51-244-0282 E-mail: [email protected] Key Words Pituicytoma; Pituitary macroadenoma; Hemorrhage; Enhancement.
INTRODUCTION CASE REPORT
Pituicytoma is a rare benign sellar and suprasellar neo- A 19-year-old man presented to our department with pro- plasm originating from the neurohypophysis or the infundib- gressive visual deterioration for 6 months. Ophthalmological ulum. The tumor is classified as a distinct entity based on the examination revealed bitemporal hemianopsia and reduced World Health Organization (WHO) classification of central visual acuity that was more apparent in his right eye (visual nervous system tumors in 2007 [1]. It is difficult to differenti- acuity: right eye, 0.2; left eye, 0.6). Hormonal evaluation re- ate pituicytomas from other sellar and suprasellar neoplasms, vealed values within normal ranges except for hypogonadism such as pituitary adenomas, meningiomas, granular cell tu- [testosterone 0.04 ng/mL (normal, 2.67–10.12 ng/mL)]. Brain mors, and pilocytic astrocytomas because of no specific ra- magnetic resonance imaging (MRI) showed a 3.8×3.1×4.5 cm diological findings and low incidence. Therefore, they are not sized highly enhancing mass expanding the sella and extend- ordinarily included in the differential diagnosis of sellar and ing into the suprasellar cistern, compressing the optic chi- suprasellar tumors. The pituicytomas are histologically be- asm, and also displacing A1 segments of the anterior cerebral nign tumors, but their hypervascularity during surgery em- arteries superiorly and anteriorly, suggestive of a pituitary barrasses surgeons because surgical removal is difficult. We macroadenoma. The tumor was hypointense on T1-weighted review and evaluate the clinical and surgical features of pitui- images and hyperintense on T2-weighted images. Intense cytomas and the relevant literatures. and homogenous enhancement are presented (Fig. 1). Based on the clinical and radiological features, the tumor was as- This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) sumed to be a pituitary macroadenoma with optic neuropathy, which permits unrestricted non-commercial use, distribution, and reproduction in any and transsphenoidal approach (TSA) was initially scheduled medium, provided the original work is properly cited. for elective surgery. However, we performed an emergency Copyright © 2017 The Korean Brain Tumor Society, The Korean Society for Neuro- Oncology, and The Korean Society for Pediatric Neuro-Oncology TSA because his vision rapidly deteriorated during preopera-
110 HK Shim et al. tive systemic evaluation for elective surgery. TSA surgery re- temporal craniotomy to prevent permanent visual loss. At vealed that the tumor had a rubbery-firm consistency, hyper- surgery, the tumor was soft, highly vascular, and appeared to vascularity, and massive bleeding. Because of unexpected be originating from the pituitary stalk. We achieved gross to- severe bleeding that needed several units of blood transfusion tal resection of the suprasellar mass to reduce compression of and confusing pathology, surgery was prematurely stopped af- the optic apparatus. The pituitary stalk could not be pre- ter only a partial resection for pathological diagnosis and ap- served due to intrinsic adhesion of the tumor. On the other plication of several hemostatic agents to control bleeding. hand, we removed the intrasellar mass subtotally because of We planned a second stage transcranial approach for de- uncontrolled bleeding from the remnant attached to both compression of the optic nerves and chiasm after digital sub- cavernous sinuses. Subsequent pathology revealed a pituicy- traction cerebral angiography. The cerebral angiogram showed toma with epithelioid features. Microscopic examination multiple feeders from both internal carotid arteries. The tumor showed a hypercellular tumor, composed of predominantly blush was noted in the mid- and late-arterial phases (Fig. 2). epithelioid cells with a vague storiform and perivascular archi- We could not perform a tumor embolization because of mul- tecture. The epithelioid tumor cells had pale eosinophilic cyto- tiple small feeders from both internal carotid arteries. Con- plasm and ovoid nuclei with small nucleoli. The tumor cells secutively, the tumor was approached through a right fronto- were positive for thyroid transcription factor (TTF)-1 and S-100
A B
C D Fig. 1. Preoperative magnetic resonance imaging. T1-weighted axial image (A) showing slightly hyperintense sellar mass, T2-weighted axi- al image (B) showing isointense sellar mass, and T1-weighted gadolinium enhanced coronal (C) and sagittal (D) images demonstrating marked enhancement of sellar-suprasellar mass with involvement of the optic nerves and chiasm.
111 Pituicytoma protein, and were focally positive for glial fibrillary acidic pro- cortisone, and DDAVP were given. In the postoperative period, tein (GFAP), which suggested the glial nature of the tumor the patient’s visual acuity and field defect improved. A postop- cells. Positive immunostaining for TTF-1 and morphologic erative MRI with gadolinium enhancement showed the re- features support the diagnosis of a pituicytoma with epitheli- sidual tumor adherent to both cavernous sinuses (Fig. 4). We oid features (Fig. 3). Postoperatively, the patient developed pan- decided to manage the residual tumor with gamma knife ra- hypopituitarism and diabetes insipidus. Levothyroxine, hydro- diosurgery. The follow-up magnetic resonance scans showed
A B Fig. 2. Angiograms of right (A) and left (B) internal carotid arteries showing significant tumor blush in the arterial phases by multiple small feeders from both internal carotid arteries.
A B
C D Fig. 3. Histopathological findings of the pituicytoma. A: The tumor cells have moderate to abundant amount of pale eosinophilic cytoplasm and ovoid nuclei with small nucleoli. Necrosis is not identified (hematoxylin and eosin staining, ×400). B: Immunohistochemistry for glial fi- brillary acidic protein shows focal positivity (×400). C: The tumor cells are positive for S100 protein (×400). D: The tumor cells show positive staining for thyroid transcription factor 1 (×400).
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A B Fig. 4. Postoperative magnetic resonance imaging after transcranial approach. T1-weighted gadolinium enhanced coronal (A) and sagittal (B) images show total removal of the suprasellar tumor that compressed the optic chiasm and remnants attached to both cavernous sinuses. the residual tumor to be stable. known because of low incidence of the tumor. The clinical symptoms of pituicytomas are variable accord- DISCUSSION ing to tumor size and location. The endocrine symptoms of a pituicytoma in the sella are not different from a typical pitu- In 1958, Liss and Kahn [2] described a tumor arising from itary adenoma, presenting sexual dysfunction that is the most the posterior part of the pituitary gland as the term “pituicyto- common endocrinopathy in sellar tumors. On the other hand, ma”. In 2000, Brat et al. [3] presented specific pathological dis- suprasellar tumors usually present with visual symptoms tinction for the diagnosis of pituicytomas. Pituicytoma was de- caused by direct compression of the optic nerves and/or chi- fined as low-grade, spindle cell astrocytic tumors that originates asm including impaired visual acuity and visual field defects in the posterior pituitary or its stalk based on the 2007 WHO [7]. Our case presented with bitemporal hemianopsia due to classification of CNS tumors [1]. In the current 2016 WHO compression of the optic chiasm similar to other suprasellar classification of CNS tumors, the term pituicytoma was re- tumors. Our patient did not have any clinical and biochemi- stricted to a distinct group of low-grade glial tumors found in cal evidence of endocrinopathy except for low testosterone the posterior pituitary and infundibulum, presumably arising before surgery. Pituicytomas have been described as solid sel- from pituicytes. Basically, the neurohypophysis is composed lar and/or suprasellar masses, typically round or oval in shape. of the posterior pituitary gland, pituitary stalk, infundibulum, The MRI scans generally show isointense on T1-weighted im- and median eminence. The cellular elements are microglia, ages, and hypointense or slightly hyperintense on T2-weight- pituicytes, and the distal nerve cells from anastomosed blood ed images. They have been presented as strong enhancement vessels and the hypothalamus. Pituicytes are considered to be after administration of contrast agents[ 2,7,8]. Marked homog- modified neuroglial cells and positive immunohistochemical enous enhancement demonstrates a highly vascular tumor. staining for GFAP. TTF-1 is strongly expressed in fetal and Most of the reported cases in the literature were primarily in- adult human pituicytes. It is also expressed in the normal de- terpreted as pituitary macroadenomas or meningiomas as in velopment of the ventral forebrain and pituitary gland. Lee et our case. They can exhibit sellar enlargement and bony re- al. [4] reported that TTF-1 is specifically expressed in pitui- modeling similar to changes of the sellar floor by pituitary cytomas, granular cell tumors, and spindle cell oncocytomas, macroadenomas. In cerebral angiography of pituicytomas, and is also useful for distinguishing them from other sellar Gibbs et al. [9] showed that a tumor was visible during the ve- tumors. Primary tumors that arise in the neurohypophysis are nous phase of selective internal carotid angiography, and rare, and are reported as many different diagnosis such as pi- even visible during the late venous phase. The pituicytoma tuicytomas, infundibulomas, choristomas, and granular cell demonstrated rapid homogenous enhancement in the early tumors [5]. It appears to have a slight predominance in men phase of angiography, rather than the gradual enhancement (59%) and occurs most often during the middle decades( mean commonly seen with pituitary adenomas [10,11]. The rapid age, 50 years old) [6]. However, the epidemiology is not well enhancement correlates with the increased vascularity of pitui-
113 Pituicytoma cytomas, which is corroborated in our case as well as in the narrow operative space after obtaining specimen for patholog- patient with significant vascular blush on the angiogram of the ic examination. We removed the suprasellar tumor by the tran- case reported by Gibbs et al. [9] Dynamic contrast-enhanced scranial approach to decompress the optic nerves and chiasm MRI scans can assist in generating a differential diagnosis from to prevent permanent visual loss after angiography and recog- other sellar and suprasellar lesions such as pituitary adenomas nition of the unusual pathology. and meningiomas [12]. The radiological differential diagnosis We suggest that pituicytomas should be included as a differ- includes sellar and suprasellar diseases with enhancement ential diagnosis of pituitary tumors in patients with homoge- such as pituitary adenomas, meningiomas, pilocytic astrocyto- nously highly-enhanced lesions in the sellar and suprasellar mas, granular cell tumors, craniopharyngiomas, ganglioglio- area because of the potential for significant intraoperative mas, germ cell tumors, sarcoidosis, and metastatic tumors. bleeding unlike common pituitary adenomas or meningio- Since pituicytomas are extremely rare and their radiological mas, especially if the surgeon is not aware of this possibility. findings are relatively nonspecific, the diagnosis mainly depends Conflicts of Interest on pathological evaluation. The authors have no financial conflicts of interest. Surgical resection is the most important part of treatment for pituicytomas. In the largest series to date, Brat et al. [3] re- Acknowledgments ported no recurrence of the tumor in patients who underwent This work was supported by 2-year Research Grant of Pusan National total surgical resection. On the other hand, according to the University. literature [13-15], pituicytomas are reported to be much more REFERENCES vascular than other suprasellar tumors. This massive bleeding from hypervascularity during surgery is probably the main 1. Louis DN, Ohgaki H, Wiestler OD, et al. The 2007 WHO classification of tumours of the central nervous system. Acta Neuropathol 2007;114: reason to explain the high numbers of subtotal resections. In 97-109. contrast to usual pituitary adenomas, pituicytomas are highly 2. Liss L, Kahn EA. Pituicytoma, tumor of the sella turcica; a clinicopath- vascular and attached to normal anatomical structures such as ological study. J Neurosurg 1958;15:481-8. 3. 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